Furosemide (brand names: Lasix®, Salix®, Frusemide®, Disal®, Uritol®) is a loop diuretic used to treat conditions such as congestive heart failure, lung fluid retention, and certain kidney diseases. It can also be used to aid in the treatment of high blood potassium and high blood pressure. In racehorses, it has been used to prevent exercise-induced lung bleeding.

Its use in cats and dogs at labeled doses is FDA approved, however, its use at other doses or use in ferrets and other small mammals, horses, birds, and reptiles to treat various conditions is ‘off label’ or ‘extra label’. Many drugs are commonly prescribed for off label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully as their directions may be significantly different from those on the label.


Furosemide, marketed under the brand name Lasix, usually is prescribed for dogs diagnosed with congestive heart failure or fluid in the lungs. Lasix is a diuretic, removing excess fluid from the body. While the drug is generally safe when used as directed, some dogs can experience side effects. Since it’s likely your dog is already seriously ill if taking Lasix, call your vet immediately if your pet experiences any side effects.

Vets prescribe Lasix more often than any other diuretic. It works by preventing the body from absorbing potassium, sodium and chloride. While generally prescribed in tablet form, Lasix may be given intravenously or via injection for dogs requiring immediate therapy. In addition to pulmonary edema or heart failure, your vet might prescribe Lasix if your dog exhibits signs of a phantom pregnancy, especially lactation. The medication helps get rid of excess fluid resulting in “milk,” helping to alleviate the condition.

Features of Lasix For Dogs

Furosemide is given by mouth in the form of a tablet or liquid. It may be given with or without food; however, if vomiting occurs when dosed on an empty stomach, give future doses with food or a treat. Measure liquid doses carefully. It can also be given by injection in the hospital or clinic setting.

Ensure your pet has access to plenty of fresh, clean water at all times while on this medication. Because this medication will cause frequent urination, avoid dosing this medication close to bedtime. If you are allergic to sulfa medications, you should wear gloves when handling this medication. This medication will take effect quickly, in about 1 to 2 hours, and improvement in clinical signs should follow.

Uses/Indications of Lasix For Dogs

  • Most important medication in the treatment of congestive heart failure
  • To treat fluid accumulation for reasons other than heart failure
  • Some forms of acute kidney failure
  • Elevated blood calcium levels
  • Used at low dosages in some dogs with chronic bronchitis

Adverse Effects of Lasix For Dogs

  • Increased thirst and urination (please contact us if this is not manageable)
  • Can cause dehydration in patients not drinking well, or with other diseases that cause fluid loss (kidney disease, vomiting/diarrhea)
  • May decrease levels of calcium, sodium, potassium, or magnesium, particularly In patients that are not eating well.
  • Low risk to increase blood sugar levels, altering the insulin need in diabetics
  • May cause low blood pressure and weakness in patients with pericardial effusion

Dosage and Administration

The usual dosage of Furosemide Tablets is 1 to 2 mg/lb body weight (approximately 2.5 to 5 mg/kg). A prompt diuresis usually ensues from the initial treatment. Administer orally once or twice daily at 6 to 8 hour intervals. The dosage should be adjusted to the individual’s response. In severe edematous or refractory cases, the dose may be doubled or increased by increments of 1.0 mg per pound of body weight. The established effective dose should be administered once or twice daily. The daily schedule of administration can be timed to control the period of micturition for the convenience of the client or veterinarian. Mobilization of the edema may be most efficiently and safely accomplished by utilizing an intermittent daily dose schedule, i.e., every other day or 2 to 4 consecutive days weekly.

Diuretic therapy should be discontinued after reduction of the edema, or maintained after determining a carefully programmed dosage schedule to prevent recurrence of edema. For long-term treatment, the dose can generally be lowered after the edema has once been reduced. Re-examination and consultations with the client will enhance the establishment of a satisfactorily programmed dosage schedule. Clinical examination and serum BUN, CO2and electrolyte determinations should be performed during the early period of therapy and periodically thereafter, especially in refractory cases. Abnormalities should be corrected or the drug temporarily withdrawn.

Dosage: Oral

DOG: One-half to one 50 mg scored tablet per 25 pounds body weight. One 12.5 mg scored tablet per 5 to 10 pounds body weight.

Administer once or twice daily, permitting a 6- to 8-hour interval between treatments. In refractory or severe edematous cases, the dosage may be doubled or increased by increments of 1 mg per pound body weight as recommended in preceding paragraphs, “Dosage and Administration”.

Prices of Lasix For Dogs

$20.10 – $45.99

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